First, thanks for an interesting and informative article.

If I may, the problem all humans face all the time, and the one that informs all thinking about ethics in philosophy, is the tension that the two aspects of our being constantly generates: separate, independent individuals who are social beings, living together in groups. That forces upon us the problem of governance: how can we determine what form governance--of individuals and the 'basic institutions of society'--should take? In anything other than a subsistence society, anyway, at some point some people must be required to abide by some rules they would not themselves choose (re. the rationale for Kant's "categorical imperative").

That is why the 'Enlightenment' quest for universal rules for governance was a great step forward for humanity. The problem isn't that those thinkers were too rational; the problem is that they were not rational enough: they reasoned from non-rational premises (beliefs, 'first principles', 'self-evident truths', etc.: examples of what Richard Dien Winfield, who is no postmodernist--he 'self-identifies' as a "neo-Hegelian"--described, in Reason and Justice, as the "privileged givens" and "privileged determiners" that have informed thinking about justice for a long as humans have been thinking about it--or at least writing about it).

The engagement of our rational faculty with material existence provides the only possible universally verifiable knowledge. It is therefore there that we must seek a universal ethic to govern governance.

I am convinced that I have found one. If curious: "From Locke to Hume to Kant to Hegel to 'Real Justice'" (here in Medium, but not behind the paywall). It’s only a “4 min read,” though it does link to more about it.